The present invention relates to an analog-to-digital (A/D) converter for converting an analog input current into a digital value.
Japanese Laid-Open Patent Publication No. 8-79080 describes a current mode A/D converter for converting an analog input signal current into a digital value. The A/D converter has a hierarchical tree configuration that is formed by a plurality of current mirror circuits. An input signal current is distributed to a plurality of branched current paths in the A/D converter. As the input signal current propagates through the current paths, the input signal current is subjected to hierarchical computation including subtraction and addition using a reference current. The resulting current is finally compared with the reference current. As a result, the A/D converter outputs a digital value.